Computer system utilizing multiple computer modules with password protection

ABSTRACT

A computer system for multi-processing purposes. The computer system has a console comprising a first coupling site and a second coupling site. Each coupling site comprises a connector. The console is an enclosure that is capable of housing each coupling site. The system also has a plurality of computer modules, where each of the computer modules is coupled to a connector. Each of the computer modules has a processing unit, a main memory coupled to the processing unit, a graphics controller coupled to the processing unit, and a mass storage device coupled to the processing unit. Each of the computer modules is substantially similar in design to each other to provide independent processing of each of the computer modules in the computer system.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority as a continuation of U.S.nonprovisional patent application Ser. No. 11/097,694, filed Mar. 31,2005, which is a continuation of U.S. nonprovisional patent applicationSer. No. 10/772,214, filed Feb. 3, 2004 now U.S. Pat. No. 7,099,981,which is a continuation of U.S. nonprovisional patent application Ser.No. 09/569,758, filed May 12, 2000 (Now U.S. Pat. No. 6,718,415), whichclaimed priority to U.S. Provisional Application No. 60/134,122 filedMay 14, 1999, commonly assigned, and hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to computing devices. More particularly,the present invention provides a system including a plurality ofcomputer modules that can independently operate to provide backupcapability, dual processing, and the like. Merely by way of example, thepresent invention is applied to a modular computing environment for desktop computers, but it will be recognized that the invention has a muchwider range of applicability. It can be applied to a server as well asother portable or modular computing applications.

Many desktop or personal computers, which are commonly termed PCs, havebeen around and used for over ten years. The PCs often come withstate-of-art microprocessors such as the Intel Pentium™ microprocessorchips. They also include a hard or fixed disk drive such as memory inthe giga-bit range. Additionally, the PCs often include a random accessmemory integrated circuit device such as a dynamic random access memorydevice, which is commonly termed DRAM. The DRAM devices now provide upto millions of memory cells (i.e., mega-bit) on a single slice ofsilicon. PCs also include a high resolution display such as cathode raytubes or CRTs. In most cases, the CRTs are at least 15 inches or 17inches or 20 inches in diameter. High resolution flat panel displays arealso used with PCs.

Many external or peripheral devices can be used with the PCs. Amongothers, these peripheral devices include mass storage devices such as aZip™ Drive product sold by Iomega Corporation of Utah. Other storagedevices include external hard drives, tape drives, and others.Additional devices include communication devices such as a modem, whichcan be used to link the PC to a wide area network of computers such asthe Internet. Furthermore, the PC can include output devices such as aprinter and other output means. Moreover, the PC can include specialaudio output devices such as speakers the like.

PCs also have easy to use keyboards, mouse input devices, and the like.The keyboard is generally configured similar to a typewriter format. Thekeyboard also has the length and width for easily inputting informationby way of keys to the computer. The mouse also has a sufficient size andshape to easily move a curser on the display from one location toanother location.

Other types of computing devices include portable computing devices suchas “laptop” computers and the like. Although somewhat successful, laptopcomputers have many limitations. These computing devices have poordisplay technology. In fact, these devices often have a smaller flatpanel display that has poor viewing characteristics. Additionally, thesedevices also have poor input devices such as smaller keyboards and thelike. Furthermore, these devices have limited common platforms totransfer information to and from these devices and other devices such asPCs.

Up to now, there has been little common ground between these platformsincluding the PCs and laptops in terms of upgrading, ease-of-use, cost,performance, and the like. Many differences between these platforms,probably somewhat intentional, has benefited computer manufacturers atthe cost of consumers. A drawback to having two separate computers isthat the user must often purchase both the desktop and laptop to have“total” computing power, where the desktop serves as a “regular”computer and the laptop serves as a “portable” computer. Purchasing bothcomputers is often costly and runs “thousands” of dollars. The user alsowastes a significant amount of time transferring software and databetween the two types of computers. For example, the user must oftencouple the portable computer to a local area network (i.e., LAN), to aserial port with a modem and then manually transfer over files and databetween the desktop and the portable computer. Alternatively, the useroften must use floppy disks to “zip” up files and programs that exceedthe storage capacity of conventional floppy disks, and transfer thefloppy disk data manually.

Another drawback with the current model of separate portable and desktopcomputer is that the user has to spend money to buy components andperipherals the are duplicated in at least one of these computers. Forexample, both the desktop and portable computers typically include harddisk drives, floppy drives, CD-ROMs, computer memory, host processors,graphics accelerators, and the like. Because program software andsupporting programs generally must be installed upon both hard drives inorder for the user to operate programs on the road and in the office,hard disk space is often wasted.

One approach to reduce some of these drawbacks has been the use of adocking station with a portable computer. Here, the user has theportable computer for “on the road” use and a docking station thathouses the portable computer for office use.

Similar to separate desktop and portable computers, there is nocommonality between two desktop computers. To date, most personalcomputers are constructed with a single motherboard that providesconnection for CPU and other components in the computer. Dual CPUsystems have been available through Intel's slot 1 architecture. Forexample, two Pentium II cartridges can be plugged into two “slot 1” cardslots on a motherboard to form a Dual-processor system. The two CPU'sshare a common host bus that connects to the rest of the system, e.g.main memory, hard disk drive, graphics subsystem, and others. Dual CPUsystems have the advantage of increased CPU performance for the wholesystem. Adding a CPU cartridge requires no change in operating systemsand application software. However, dual CPU systems may suffer limitedperformance improvement if memory or disk drive bandwidth becomes thelimiting factor. Also, dual CPU systems have to time-share theprocessing unit in running multiple applications. CPU performanceimprovement efficiency also depends on software coding structure. DualCPU systems provide no hardware redundancy to help fault tolerance. Inrunning multiple applications, memory and disk drive data throughputwill become the limiting factor in improving performance withmulti-processor systems.

The present invention generally relates to computer interfaces. Morespecifically, the present invention relates to an interface channel thatinterfaces two computer interface buses that operate under protocolsthat are different from that used by the interface channel.

Interfaces coupling two independent computer buses are well known in theart. A block diagram of a computer system utilizing such a prior artinterface is shown in FIG. 5. In FIG. 5, a primary peripheral componentinterconnect (PCI) bus 505 of a notebook PC 500 is coupled to asecondary PCI bus 555 in a docking system 550 (also referred to asdocking station 550) through high pin count connectors 501 and 502,which are normally mating connectors. The high pin count connectors 501and 502 contain a sufficiently large number of pins so as to carry PCIbus signals between the two PCI buses without any translation. The mainpurpose for interfacing the two independent PCI buses is to allowtransactions to occur between a master on one PCI bus and a target onthe other PCI bus. The interface between these two independent PCI busesadditionally includes an optional PCI to PCI bridge 560, located in thedocking station 550, to expand the add on capability in docking station550. The bridge 560 creates a new bus number for devices behind thebridge 560 so that they are not on the same bus number as other devicesin the system thus increasing the add on capability in the dockingstation 550.

An interface such as that shown in FIG. 5 provides an adequate interfacebetween the primary and secondary PCI buses. However, the interface islimited in a number of ways. The interface transfers signals between theprimary and secondary PCI buses using the protocols of a PCI bus.Consequently, the interface is subject to the limitations under whichPCI buses operate. One such limitation is the fact that PCI buses arenot cable friendly. The cable friendliness of the interface was not amajor concern in the prior art. However, in the context of the computersystem of the present invention, which is described in the presentinventor's (William W.Y. Chu's) application for “Personal ComputerPeripheral Console With Attached Computer Module” filed concurrentlywith the present application on Sep. 8, 1998 and incorporated herein byreference, a cable friendly interface is desired for interfacing anattached computer module (ACM) and a peripheral console of the presentinvention. Furthermore, as a result of operating by PCI protocols, theprior art interface includes a very large number of signal channels witha corresponding large number of conductive lines (and a similarly largenumber of pins in the connectors of the interface) that are commensuratein number with the number of signal lines in the PCI buses which itinterfaces. One disadvantage of an interface having a relatively largenumber of conductive lines and pins is that it costs more than one thatuses a fewer number of conductive lines and pins. Additionally, aninterface having a large number of conductive lines is bulkier and morecumbersome to handle. Finally, a relatively large number of signalchannels in the interface renders the option of using differentialvoltage signals less viable because a differential voltage signal methodwould require duplicating a large number of signal lines. It isdesirable to use a low voltage differential signal (LVDS) channel in thecomputer system of the present invention because an LVDS channel is morecable friendly, faster, consumes less power, and generates less noise,including electromagnetic interferences (EMI), than a PCI channel. Theterm LVDS is herein used to generically refer to low voltagedifferential signals and is not intended to be limited to any particulartype of LVDS technology.

Thus, what is needed are computer systems that can have multiplecomputer modules. Each computer module has dedicated memory and diskdrive, and can operate independently.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, a technique including a method anddevice for multi-module computing is provided. In an exemplaryembodiment, the present invention provides a system including aplurality of computer modules that can independently operate to providebackup capability, dual processing, and the like.

In a specific embodiment, the present invention provides a computersystem for multi-processing purposes. The computer system has a consolecomprising a first coupling site and a second coupling site, e.g.,computer module bay. Each coupling site comprises a connector. Theconsole is an enclosure that is capable of housing each coupling site.The system also has a plurality of computer modules, where each of thecomputer modules is coupled to one of the connectors. Each of thecomputer modules has a processing unit, a main memory coupled to theprocessing unit, a graphics controller coupled to the processing unit,and a mass storage device coupled to the processing unit. Each of thecomputer modules is substantially similar in design to each other toprovide independent processing of each of the computer modules in thecomputer system.

In an alternative specific embodiment, the present invention provides amulti-processing computer system. The system has a console comprising afirst coupling site and a second coupling site. Each coupling sitecomprises a connector. The console is an enclosure that is capable ofhousing each coupling site. The system also has a plurality of computermodules, where each of the computer modules is coupled to one of theconnectors. Each of the computer modules has a processing unit, a mainmemory coupled to the processing unit, a graphics controller coupled tothe processing unit, a mass storage device coupled to the processingunit, and a video output coupled to the processing unit. Each of thecomputer modules is substantially similar in design to each other toprovide independent processing of each of the computer modules in thecomputer system. A video switch circuit is coupled to each of thecomputer modules through the video output. The video switch isconfigured to switch a video signal from any one of the computer modulesto a display.

Numerous benefits are achieved using the present invention overpreviously existing techniques. In one embodiment, the inventionprovides improved processing and maintenance features. The invention canalso provide increased CPU performance for the whole system. Theinvention also can be implemented without changes in operating systemand application software. The present invention is also implementedusing conventional technologies that can be provided in the presentcomputer system in an easy and efficient manner.

In another embodiment, the invention provides at least two users toshare the same modular desktop system. Each user operates on a differentcomputer module. The other peripheral devices, i.e. CDROM, printer, DSLconnection, etc. can be shared. This provides lower system cost, lessdesktop space and more efficiency. Depending upon the embodiment, one ormore of these benefits can be available. These and other advantages orbenefits are described throughout the present specification and aredescribed more particularly below.

In still further embodiments, the present invention provides methods ofusing multiple computer modules.

The present invention encompasses an apparatus for bridging a firstcomputer interface bus and a second computer interface bus, where eachof the first and second computer interface buses have a number ofparallel multiplexed address/data bus lines and operate at a clock speedin a predetermined clock speed range having a minimum clock speed and amaximum clock speed. The apparatus comprises an interface channel havinga clock line and a plurality of bit lines for transmitting bits; a firstinterface controller coupled to the first computer interface bus and tothe interface channel to encode first control signals from the firstcomputer interface bus into first control bits to be transmitted on theinterface channel and to decode second control bits received from theinterface channel into second control signals to be transmitted to thefirst computer interface bus; and a second interface controller coupledto the interface channel and the second computer interface bus to decodethe first control bits from the interface channel into third controlsignals to be transmitted on the second computer interface bus and toencode fourth control signals from the second computer interface businto the second control bits to be transmitted on the interface channel.

In one embodiment, the first and second interface controllers comprise ahost interface controller (HIC) and a peripheral interface controller(PIC), respectively, the first and second computer interface busescomprise a primary PCI and a secondary PCI bus, respectively, and theinterface channel comprises an LVDS channel.

The present invention overcomes the aforementioned disadvantages of theprior art by interfacing two PCI or PCI-like buses using a non-PCI ornon-PCI-like channel. In the present invention, PCI control signals areencoded into control bits and the control bits, rather than the controlsignals that they represent, are transmitted on the interface channel.At the receiving end, the control bits representing control signals aredecoded back into PCI control signals prior to being transmitted to theintended PCI bus.

The fact that control bits rather than control signals are transmittedon the interface channel allows using a smaller number of signalchannels and a correspondingly small number of conductive lines in theinterface channel than would otherwise be possible. This is because thecontrol bits can be more easily multiplexed at one end of the interfacechannel and recovered at the other end than control signals. Thisrelatively small number of signal channels used in the interface channelallows using LVDS channels for the interface. As mentioned above, anLVDS channel is more cable friendly, faster, consumes less power, andgenerates less noise than a PCI bus channel, which is used in the priorart to interface two PCI buses. Therefore, the present inventionadvantageously uses an LVDS channel for the hereto unused purpose ofinterfacing PCI or PCI-like buses. The relatively smaller number ofsignal channels in the interface also allows using connectors havingsmaller pins counts. As mentioned above an interface having a smallernumber of signal channels and, therefore, a smaller number of conductivelines is less bulky and less expensive than one having a larger numberof signal channels. Similarly, connectors having a smaller number ofpins are also less expensive and less bulky than connectors having alarger number of pins.

In one embodiment, the present invention encompasses an apparatus forbridging a first computer interface bus and a second computer interfacebus, in a microprocessor based computer system where each of the firstand second computer interface buses have a number of parallelmultiplexed address/data bus lines and operate at a clock speed in apredetermined clock speed range having a minimum clock speed and amaximum clock speed. The apparatus comprises an interface channel havinga clock channel and a plurality of bit channels for transmitting bits; afirst interface controller coupled to the first computer interface busand to the interface channel to encode first control signals from thefirst computer interface bus into first control bits to be transmittedon the interface channel and to decode second control bits received fromthe interface channel into second control signals to be transmitted tothe first computer interface bus; and a second interface controllercoupled to the interface channel and the second computer interface busto decode the first control bits from the interface channel into thirdcontrol signals to be transmitted on the second computer interface busand to encode fourth control signals from the second computer interfacebus into the second control bits to be transmitted on the interfacechannel.

In one embodiment, the first and second interface controllers comprise ahost interface controller (HIC) and a peripheral interface controller(PIC), respectively, the first and second computer interface busescomprise a primary PCI and a secondary PCI bus, respectively, and theinterface channel comprises an LVDS channel.

In a preferred embodiment, the interface channel has a plurality ofserial bit channels numbering fewer than the number of parallel buslines in each of the PCI buses and operates at a clock speed higher thanthe clock speed at which any of the bus lines operates. Morespecifically, the interface channel includes two sets of unidirectionalserial bit channels which transmit data in opposite directions such thatone set of bit channels transmits serial bits from the HIC to the PICwhile the other set transmits serial bits from the PIC to the HIC. Foreach cycle of the PCI clock, each bit channel of the interface channeltransmits a packet of serial bits.

The HIC and PIC each include a bus controller to interface with thefirst and second computer interface buses, respectively, and to managetransactions that occur therewith. The HIC and PIC also include atranslator coupled to the bus controller to encode control signals fromthe first and second computer interface buses, respectively, intocontrol bits and to decode control bits from the interface channel intocontrol signals. Additionally, the HIC and PIC each include atransmitter and a receiver coupled to the translator. The transmitterconverts parallel bits into serial bits and transmits the serial bits tothe interface channel. The receiver receives serial bits from theinterface channel and converts them into parallel bits.

According to the present invention, a technique including a method anddevice for securing a computer module using a password in a computersystem is provided. In an exemplary embodiment, the present inventionprovides a security system for an attached computer module “ACM”). In anembodiment, the ACM inserts into a Computer Module Bay (CMB) within aperipheral console to form a functional computer.

In a specific embodiment, the present invention provides a computermodule. The computer module has an enclosure that is insertable into aconsole. The module also has a central processing unit (i.e., integratedcircuit chip) in the enclosure. The module has a hard disk drive in theenclosure, where the hard disk drive is coupled to the centralprocessing unit. The module further has a programmable memory device inthe enclosure, where the programmable memory device can be configurableto store a password for preventing a possibility of unauthorized use ofthe hard disk drive and/or other module elements. The stored passwordcan be any suitable key strokes that a user can change from time totime. In a further embodiment, the present invention provides apermanent password or user identification code stored in flash memory,which also can be in the processing unit, or other integrated circuitelement. The permanent password or user identification code is designedto provide a permanent “finger print” on the attached computer module.

In a specific embodiment, the present invention provides a variety ofmethods. In one embodiment, the present invention provides a method foroperating a computer system such as a modular computer system andothers. The method includes inserting an attached computer module “ACM”)into a bay of a modular computer system. The ACM has a microprocessorunit (e.g., microcontroller, microprocessor) coupled to a mass memorystorage device (e.g., hard disk). The method also includes applyingpower to the computer system and the ACM to execute a security program,which is stored in the mass memory storage device. The method alsoincludes prompting for a user password from a user on a display (e.g.,flat panel, CRT). In a further embodiment, the present method includes astep of reading a permanent password or user identification code storedin flash memory, or other integrated circuit element. The permanentpassword or user identification code provides a permanent finger printon the attached computer module. The present invention includes avariety of these methods that can be implemented in computer codes, forexample, as well as hardware.

Numerous benefits are achieved using the present invention overpreviously existing techniques. The present invention providesmechanical and electrical security systems to prevent theft orunauthorized use of the computer system in a specific embodiment.Additionally, the present invention substantially prevents accidentalremoval of the ACM from the console. In some embodiments, the presentinvention prevents illegal or unauthorized use during transit. Thepresent invention is also implemented using conventional technologiesthat can be provided in the present computer system in an easy andefficient manner. Depending upon the embodiment, one or more of thesebenefits can be available. These and other advantages or benefits aredescribed throughout the present specification and are described moreparticularly below.

These and other embodiments of the present invention, as well as itsadvantages and features, are described in more detail in conjunctionwith the text below and attached Figs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram of a computer system according to anembodiment of the present invention;

FIG. 2 is a simplified block diagram of a computer system according toan alternative embodiment of the present invention;

FIG. 3 is a simplified block diagram of a computer system according to afurther alternative embodiment of the present invention; and

FIG. 4 is a simplified flow diagram of a method according to anembodiment of the present invention.

FIG. 5 is a block diagram of a computer system using a prior artinterface between a primary and a secondary PCI bus.

FIG. 6 is a block diagram of one embodiment of a computer system usingthe interface of the present invention.

FIG. 7 is a partial block diagram of a computer system using theinterface of the present invention as a bridge between the north andsouth bridges of the computer system.

FIG. 8 is a partial block diagram of a computer system in which thenorth and south bridges are integrated with the host and peripheralinterface controllers, respectively.

FIG. 9 is a block diagram of one embodiment of the host interfacecontroller and the peripheral interface controller of the presentinvention.

FIG. 10 is a detailed block diagram of one embodiment of the hostinterface controller of the present invention.

FIG. 11 is a detailed block diagram of one embodiment of the PIC of thepresent invention.

FIG. 12 is a table showing the symbols, signals, data rate anddescription of signals in a first embodiment of the XPBus.

FIG. 13 is a table showing the information transmitted on the XPBusduring two clock cycles of the XPBus in one embodiment of the presentinvention where 10 data bits transmitted in each clock cycle of theXPBus.

FIG. 14 is a table showing information transmitted on the XPBus duringfour clock cycles of the XPBus in another embodiment of the presentinvention where 10 data bits are transmitted in each clock cycle of theXPBus.

FIG. 15 is a schematic diagram of the signal lines PCK, PD0 to PD3, andPCN.

FIG. 16 is a table showing the names, types, number of pins dedicatedto, and the description of the primary bus PCI signals.

FIG. 17 is a simplified layout diagram of a security system for acomputer system according to an embodiment of the present invention.

FIG. 18 is a simplified block diagram of a security system for acomputer module according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, a technique including a method anddevice for multi-module computing is provided. In an exemplaryembodiment, the present invention provides a system including aplurality of computer modules that can independently operate to providebackup capability, dual processing, and the like.

FIG. 1 is a simplified diagram of a computer system 100 according to anembodiment of the present invention. This diagram is merely anillustration and should not limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,modifications, and alternatives. The computer system 100 includes anattached computer module (i.e., ACM) 113, a desktop console 101, amongother elements. The computer system also has another ACM module 117.Each ACM module has a respective slot 121, 119, which mechanicallyhouses and electrically couples each ACM to the computer console. Alsoshown is a display 111, which connects to the console. Additionally,keyboard 109 and mouse 115 are also shown. A second display 102,keyboard 105, and mouse 107 can be coupled to the console in someoptional embodiments to allow more than one user to operate the computersystem. The computer system is modular and has a variety of componentsthat are removable. Some of these components (or modules) can be used indifferent computers, workstations, computerized television sets, andportable or laptop units.

In the present embodiment, each ACM 113 includes computer components, aswill be described below, including a central processing unit “CPU”), IDEcontroller, hard disk drive, computer memory, and the like. The computermodule bay (i.e., CMB) 121 is an opening or slot in the desktop console.The CMB houses the ACM and provides communication to and from the ACM.The CMB also provides mechanical protection and support to the ACM. TheCMB has a mechanical alignment mechanism for mating a portion of the ACMto the console. The CMB further has thermal heat dissipation sinks,electrical connection mechanisms, and the like. Some details of the ACMcan be found in co-pending patent application Ser. Nos. 09/149,882 and09/149,548 filed Sep. 8, 1998, commonly assigned, and herebyincorporated by reference for all purposes.

In a specific embodiment, the present multiple computer module systemhas a peripheral console that has two or more computer bays that canreceive a removable computer module or ACM. Multiple computer modulesystem can function as a personal computer with only one ACM and theperipheral console. The second and additional ACM can be added later toincrease overall system performance and reliability. The ACM operatesindependently as self-contained computer, communicates with each otherthrough a high-speed serial communication and share most peripheraldevices within the peripheral console. Each ACM controls its independentgraphics subsystem and drives separate video output signals. A practicalimplementation is a dual ACM system. In a dual ACM system, two monitorscan be used to display the two ACMs' graphics outputs at the same time.For a single monitor, a RGB switch is used to switch between the videooutputs of the two ACMs and can be controlled by a command from theuser. Similarly, input devices (i.e. keyboard and mouse) are switchedbetween the two computer systems with a command from the user. Commandfrom the user can be in the form of either a dedicated key on thekeyboard or a special icon on the screen that the mouse can click on.

In most embodiments, the ACM includes an enclosure such as the onedescribed with the following components, which should not be limiting:

-   -   1) A CPU with cache memory;    -   2) Core logic device or means;    -   3) Main memory;    -   4) A single primary Hard Disk Drive “HDD”) that has a security        program;    -   5) Flash memory with system BIOS and programmable user password;    -   6) Operating System, application software, data files on primary        HDD;    -   7) An interface device and connectors to peripheral console;    -   8) A software controllable mechanical lock, lock control means,        and other accessories.

The ACM connects to a peripheral console with power supply, a displaydevice, an input device, and other elements. Some details of theseelements with the present system are described in more detail below. Ina dual ACM system, the primary ACM can connect directly to theperipheral board in the peripheral console. The second ACM can connecteither directly or indirectly to the peripheral board. For indirectconnection, a receptacle board is added to allow a cable connection tothe peripheral board. This is to facilitate the mechanical positioningof the second ACM inside the computer chassis. The receptacle boardapproach can even be used for the primary ACM if a high bandwidthperipheral bus, e.g. PCI Bus, is not connected from the primary ACM tothe peripheral board.

The shared peripheral console has a chassis and a motherboard thatconnects the following devices:

-   -   1) Input means, e.g. keyboard and mouse,    -   2) Display means, e.g. RGB monitor,    -   3) Add-on means, e.g. PCI add-on slots,    -   4) Two Computer Module Bays (CMB) with connectors to two ACMs,    -   5) A serial communication Hub controller that interfaces to        serial communication controller of both ACMs,    -   6) Shared storage subsystem, e.g. Floppy drive, CDROM drive, DVD        drive, or 2nd Hard Drive,    -   7) Communication device, e.g. modem,    -   8) Power supply, and others.

The computer bay is an opening in the peripheral console that receivesan ACM. CMB provides mechanical protection to ACM, mechanical alignmentfor connector mating, mechanical locking system to prevent theft andaccidental removal, and connectors at the end of the opening forconnecting to ACM. The interface bus between ACM and the peripheralconsole has a video bus, peripheral connections, serial communicationconnection, control signals and power connection. Video bus includesvideo output of graphics devices, i.e. analog RGB and control signalsfor monitor. Power connection supplies the power for ACM.

An implementation of peripheral sharing is the use of Ethernetcontrollers to bridge the communication between the two ACMs. Some ofthe peripheral devices residing in the peripheral console are shown inthe simplified diagram of FIG. 2. As shown, the diagram is merely anillustration which should not limit the scope of the claims herein. Oneof ordinary skill in the art would recognize many other variations,alternatives, and modifications. As shown, a primary ACM 203 isconnected to PCI peripheral devices in the peripheral console throughthe PCI bus 225 that passes through the connection between primary ACM203 and peripheral console 201. As shown, ACM has a CPU module 207coupled to the PCI bus through a North Bridge 211.

The CPU module can use a suitable microprocessing unit, microcontroller,digital signal processor, and the like. In a specific embodiment, theCPU module uses, for example, a 400 MHz Pentium II microprocessor modulefrom Intel Corporation and like microprocessors from AMD Corporation,Cyrix Corporation (now National Semiconductor Corporation), and others.In other aspects, the microprocessor can be one such as the CompaqComputer Corporation Alpha Chip, Apple Computer Corporation PowerPC G3processor, and the like. Further, higher speed processors arecontemplated in other embodiments as technology increases in the future.

In the CPU module, peripheral controller 213 is coupled to BIOS/flashmemory 217. Additionally, the peripheral controller is coupled to aclock control logic, a configuration signal, and a peripheral bus. TheACM has the hard drive module 215. Among other elements, the ACMincludes north bridge 215, graphics subsystem 223 (e.g., graphicsaccelerator, graphics memory), an IDE controller, and other components.Adjacent to and in parallel alignment with the hard drive module 215 isthe PCI bus. In a specific embodiment, North Bridge unit 211 oftencouples to a computer memory 209, to the graphics subsystem, and to theperipheral controller via the PCI bus. Graphics subsystem typicallycouples to a graphics memory, and other elements. IDE controllergenerally supports and provides timing signals necessary for the IDEbus. In the present embodiment, the IDE controller is embodied as partof a P114XE controller from Intel, for example. Other types of busesthan IDE are contemplated, for example EIDE, SCSI, 1394, and the like inalternative embodiments of the present invention.

The hard drive module or mass storage unit 215 typically includes acomputer operating system, application software program files, datafiles, and the like. In a specific embodiment, the computer operatingsystem may be the Windows98 operating system from Microsoft Corporationof Redmond Wash. Other operating systems, such as WindowsNT, MacOS8,Unix, and the like are also contemplated in alternative embodiments ofthe present invention. Further, some typical application softwareprograms can include Office98 by Microsoft Corporation, Corel PerfectSuite by Corel, and others. Hard disk module 215 includes a hard diskdrive. The hard disk drive, however, can also be replaced by removablehard disk drives, read/write CD ROMs, flash memory, floppy disk drives,and the like. A small form factor, for example 2.5″, is currentlycontemplated, however, other form factors, such as PC card, and the likeare also contemplated. Mass storage unit 240 may also support otherinterfaces than IDE.

Among other features, the computer system includes an ACM with securityprotection.

The ACM also has a network controller, which can be an Ethernetcontroller 219, which is coupled to the North Bridge through the PCIbus. The North Bridge is coupled to the CPU. The Ethernet controller canbe a 10/100 Base, such as Intel's 82559 or the like. Other types ofnetwork connection devices can also be used. For example, the inventioncan use Gbit Ethernet 1394, and USB 2.0. The network controller couplesto a hub 233 in the console, which includes shared peripheral system201.

Also shown is the second ACM 205. The second ACM has the same or similarcomponents as the first ACM. Here, like reference numerals have beenused for easy cross-referencing, but is not intended to be limiting. Insome embodiments, the secondary ACM is not connected to the PCI bus inthe peripheral console directly. The secondary ACM 219 accessesperipheral devices controlled by the primary ACM through the Ethernetconnection to the primary ACM, e.g. CD-ROM, or PCI modem. Theimplementation is not restricted to Ethernet serial communication andcan use other high-speed serial communication such as USB 2.0, and 1394.The Ethernet hub is coupled to an external output port 235, whichconnects to an external network.

The primary hard disk drive in each ACM can be accessed by the other ACMas sharable hard drive through the Ethernet connection. This allows theeasy sharing of files between the two independent computer modules. TheEthernet Hub Controller provides the high-speed communication functionbetween the two computer modules. Ethernet data bandwidth of 100Mbit/sec allows fast data communication between the two computermodules. The secondary ACM access peripheral devices of the primary ACMthrough the network connection provided by Ethernet link. The operatingsystem, e.g. Windows 98, provides the sharing of resources between thetwo ACMs. In some embodiments, critical data in one ACM can be backupinto the other ACM.

The Ethernet hub also couples to PCI bus 239, which connects to PCIdevices 241, 243, e.g., modem, SCSI controller. A flash memory 242 canalso be coupled to the PCI bus. The flash memory can store passwords andsecurity information, such as those implementations described in U.S.Ser. No. 09/183,493, which is commonly owned, and hereby incorporated byreference. The hub 233 also couples to an I/O control 237, whichconnects to keyboard/mouse switch 245, which couples to keyboard/mouse247. Optionally, the keyboard/mouse switch also couples to a secondkeyboard/house 259 via PS2 or USB signal line 251. The keyboard/mouseswitch has at least a first state and a second state, which allowoperation of respectively multiple keyboards or a single keyboard. Theswitch also couples to each I/O controller 221 in each ACM via lines253, 255. The I/O control 237 also couples to an RGB switch 257, whichallows video signals to pass to the first monitor 259. Alternatively,the RGB switch couples to a second monitor 261. The RGB switch includesanalog video switches such as MAXIM's MAX4545.

The peripheral system 201 also has an independent power supply 231 foreach ACM. Each power supply provides power to each ACM. As merely anexample, the power supply is a MICRO ATX 150W made by ENLIGHT, but canbe others. The power supply is connected or coupled to each ACM througha separate line, for example. The independent power supply allows forindependent operation of each ACM in some embodiments.

The above embodiments are described generally in terms of hardware andsoftware. It will be recognized, however, that the functionality of thehardware can be further combined or even separated. The functionality ofthe software can also be further combined or even separated. Hardwarecan be replaced, at times, with software. Software can be replaced, attimes, with hardware. Accordingly, the present embodiments should not beconstrued as limiting the scope of the claims here. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives.

FIG. 3 is a simplified block diagram 300 of a computer system accordingto an alternative embodiment of the present invention. This diagram ismerely an example which should not limit the scope of the claims herein.One of ordinary skill in the art would recognizes many other variations,modifications, and alternatives. Like reference numerals are used inthis FIG. as the previous FIGS. for easy referencing, but are notintended to be limiting. As shown, each ACM includes common elements asthe previous FIG. A primary ACM 203 is connected to PCI peripheraldevices in the peripheral console through the PCI bus 225 that passesthrough the connection between primary ACM 203 and peripheral console201. As shown, ACM has a CPU module 207 coupled to the PCI bus through aNorth Bridge 211.

The CPU module can use a suitable microprocessing unit, microcontroller,digital signal processor, and the like. In a specific embodiment, theCPU module uses, for example, a 400 MHz Pentium II microprocessor modulefrom Intel Corporation and like microprocessors from AMD Corporation,Cyrix Corporation (now National Semiconductor Corporation), and others.In other aspects, the microprocessor can be one such as the CompaqComputer Corporation Alpha Chip, Apple Computer Corporation PowerPC G3processor, and the like. Further, higher speed processors arecontemplated in other embodiments as technology increases in the future.

In the CPU module, peripheral controller 213 is coupled to BIOS/flashmemory 217. Additionally, the peripheral controller is coupled to aclock control logic, a configuration signal, and a peripheral bus. TheACM has the hard drive module 215. Among other elements, the ACMincludes north bridge 215, graphics subsystem 223 (e.g., graphicsaccelerator, graphics memory), an IDE controller, and other components.Adjacent to and in parallel alignment with the hard drive module 215 isthe PCI bus. In a specific embodiment, North Bridge unit 211 oftencouples to a computer memory 209, to the graphics subsystem, and to theperipheral controller via the PCI bus. Graphics subsystem typicallycouples to a graphics memory, and other elements. IDE controllergenerally supports and provides timing signals necessary for the IDEbus. In the present embodiment, the IDE controller is embodied as partof a P114XE controller from Intel, for example. Other types of busesthan IDE are contemplated, for example EIDE, SCSI, 1394, and the like inalternative embodiments of the present invention.

The hard drive module or mass storage unit 215 typically includes acomputer operating system, application software program files, datafiles, and the like. In a specific embodiment, the computer operatingsystem may be the Windows98 operating system from Microsoft Corporationof Redmond Wash. Other operating systems, such as WindowsNT, MacOS8,Unix, and the like are also contemplated in alternative embodiments ofthe present invention. Further, some typical application softwareprograms can include Office98 by Microsoft Corporation, Corel PerfectSuite by Corel, and others. Hard disk module 215 includes a hard diskdrive. The hard disk drive, however, can also be replaced by removablehard disk drives, read/write CD ROMs, flash memory, floppy disk drives,and the like. A small form factor, for example 2.5″, is currentlycontemplated, however, other form factors, such as PC card, and the likeare also contemplated. Mass storage unit 240 may also support otherinterfaces than IDE.

Among other features, the computer system includes an ACM with securityprotection.

The ACM also has a network controller, which can be coupled to a serialport 302, which is coupled to the PCI bus in the ACM. The serial port iscoupled to the peripheral console through a serial controller 301 in theserial console. The serial controller is connected to PCI bus 239. Theserial controller is also coupled to a serial hub controller 303, whichis coupled to the PCI bus and a second ACM. In a specific embodiment, areceptacle board 310 is added to connect to the second ACM. The purposeof the receptacle board is to allow a cable connection 307 to theperipheral board 300. The cable connection is possible because thesignals needed to connect to the peripheral board can be limited tovideo, I/O, serial communication, and power. The serial communicationcontroller can be placed on the receptacle board and not in the ACM. Asshown, the serial bus controller couples to the PCI bus. The receptacleboard also couples to power, graphics subsystem, I/O controller, andother elements, which may be on a common bus. The overall operation ofthe present configuration is similar to the previous one except itoperates in serial communication mode.

The Dual ACM system can support different usage models:

1. One user using both ACMs concurrently with 1 or 2 monitors, and acommon keyboard/mouse.

2. Two users using the two separate ACMs at the same time with separatemonitors and keyboard/mouse. The 2 users share peripherals, e.g.,printer, CDROM, and others. The two users share external networking.

To support 1 monitor for both ACMs, a video switch in the peripheralconsole is used to switch between the video outputs of the two ACMs. Thesystem can be set to support either 1 monitor or 2-monitor mode. Theuser presses a special key on the keyboard or a special icon on thescreen to switch the screen display from one ACM to the other. This sameaction causes the keyboard and mouse connections to switch from one ACMto the other ACM.

A dual ACM system can save space, wiring, and cost for a 2-person PCsetup, with the added benefit that both PC systems can be accessed fromone user site for increased system performance if the other user is notusing the system. Files can be copied between the primary drive of bothsystem and provides protection against a single ACM failure. Softwareneeds to be developed to manage the concurrent use of two PC subsystems,the automatic sharing of selected files between the two systems, andfault tolerance.

The design with more than two computer modules can be implemented withthe use of multi-port, serial communication hub controller andmulti-port I/O switches. In one embodiment, a peripheral console hasfour computer bays for four separate computer modules. The computermodules communicate through a four port Ethernet hub. The video,keyboard, and mouse switch will cycle through the connection from eachcomputer module to the external monitor, keyboard, and mouse with a pushbutton sequentially. This embodiment is useful for a server thatperforms different functions concurrently, e.g. email, applicationhosting, web hosting, firewall, etc.

The above embodiments are described generally in terms of hardware andsoftware. It will be recognized, however, that the functionality of thehardware can be further combined or even separated. The functionality ofthe software can also be further combined or even separated. Hardwarecan be replaced, at times, with software. Software can be replaced, attimes, with hardware. Accordingly, the present embodiments should not beconstrued as limiting the scope of the claims here. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives.

FIG. 4 is a simplified diagram of a method according to an embodiment ofthe present invention. This diagram is merely an example which shouldnot limit the scope of the claims herein. One of ordinary skill in theart would recognize many other variations, modifications, andalternatives. The present diagram illustrates an automatic file backupprocedure from one computer module to the other. As shown, a userselects (step 401) a certain file in one of the computer module forautomatic backup. Next, the method determines if another module isavailable, step 403. If so, the method in the originating modulerequests the other computer module to create (step 405) backup file.Alternatively, the method alerts the user of the missing ormalfunctioning module, step 429. The method then has the user try later431, once the missing or malfunctioning module has been replaced orrepaired. Next, the method determines if there is sufficient storageavailable in the other computer module for the backup files. If so, themethod goes to the next step. (Alternatively, the method prompts (step433) a message to the user indicating that the storage is full.) In thenext step, the method stores the backup file in memory of the othermodule. After the backup file has been successfully created (step 409),the software in the originating ACM sets a timer to check (step 411) forfile modification via branches 423, 427 through continue, step 425process. If a file selected for backup has been modified (step 415),then the file is automatically back up to the other ACM again, step 417.Alternatively, the method returns to step 411 through branch 421.

The above embodiments are described generally in terms of hardware andsoftware. It will be recognized, however, that the functionality of thehardware can be further combined or even separated. The functionality ofthe software can also be further combined or even separated. Hardwarecan be replaced, at times, with software. Software can be replaced, attimes, with hardware. Accordingly, the present embodiments should not beconstrued as limiting the scope of the claims here. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives.

FIG. 6 is a block diagram of one embodiment of a computer system 600using the interface of the present invention. Computer system 600includes an attached computer module (ACM) 605 and a peripheral console610, which are described in greater detail in the application of WilliamW. Y. Chu for “Personal Computer Peripheral Console With AttachedComputer Module” filed concurrently with the present application on Sep.8, 1998 and incorporated herein by reference. The ACM 605 and theperipheral console 610 are interfaced through an exchange interfacesystem (XIS) bus 615. The XIS bus 615 includes power bus 616, video bus617 and peripheral bus (XPBus) 618, which is also herein referred to asan interface channel. The power bus 616 transmits power between ACM 605and peripheral console 610. In a preferred embodiment power bus 616transmits power at voltage levels of 3.3 volts, 5 volts and 12 volts.Video bus 617 transmits video signals between the ACM 605 and theperipheral console 610. In a preferred embodiment, the video bus 617transmits analog Red Green Blue (RGB) video signals for color monitors,digital video signals (such as Video Electronics Standards Association(VESA) Plug and Display's Transition Minimized Differential Signaling(TMDS) signals for flat panel displays), and television (TV) and/orsuper video (S-video) signals. The XPBus 618 is coupled to hostinterface controller (HIC) 619 and to peripheral interface controller(PIC) 620, which is also sometimes referred to as a bay interfacecontroller.

In the embodiment shown in FIG. 6, HIC 619 is coupled to an integratedunit 621 that includes a CPU, a cache and a north bridge. In anotherembodiment, such as that shown in FIG. 7, the CPU 705 and north bridge710 are separate rather than integrated units. In yet anotherembodiment, such as that shown in FIG. 8, the HIC and PIC are integratedwith the north and south bridges, respectively, such that integrated HICand north bridge unit 805 includes an HIC and a north bridge, whileintegrated PIC and south bridge unit 810 includes a PIC and a southbridge.

FIG. 9 is a more detailed block diagram of one embodiment of an HIC 905and a PIC 955 of the present invention. HIC 905 includes a peripheralcomponent interconnect (PCI) bus controller 910, an XPBus controller915, a phase lock loop (PLL) clock 920 and an input/output (10) control925. Similarly, PIC 955 includes a PCI bus controller 960, an XPBuscontroller 965, a PLL clock 970 and an IO control 975. PCI buscontrollers 910 and 960 are coupled to the primary and secondary PCIbuses 930 and 980, respectively, and manage PCI transactions on theprimary and secondary PCI buses 930 and 980, respectively. Similarly,XPBus Controllers 915 and 965 are coupled to XPBus 990. XPBus controller915 drives the PCK line 991 and PD[0::3] and PCN lines 992 while XPBuscontroller 965 drives the PCKR lines 993, the PDR[0::3] and PCNR lines994 and the RESET# line 995.

PCI bus controller 910 receives PCI clock signals from the primary PCIbus 930 and is synchronized to the PCI clock. However, as indicated inFIG. 9, the XPBus controller 915 is asynchronous with the PCI buscontroller 910. Instead, the XPBus controller receives a clock signalfrom the PLL clock 920 and is synchronized therewith. PLL clock 920generates a clock signal independent of the PCI clock. The asynchronousoperation of the PCI bus and the XPBus allows the PCI Bus to change infrequency, for example as in a power down situation, without directlyaffecting the XPBus clocking. In the embodiment shown in FIG. 9, the PLLclock 920 generates a clock signal having a frequency of 66 MHz, whichis twice as large as the 33 MHz frequency of the PCI clock. (The clocksignal generated by the PLL clock may have a clock speed different from,including lower than, 66 MHz. For example, in another embodiment, whichis discussed in greater detail below, the PLL clock 920 generates aclock signal having a frequency of 132 MHz.)

The XPBus 990 operates at the clock speed generated by the PLL clock920. Therefore, PCK, the clock signal from the XPBus controller 915 toXPBus controller 965 has the same frequency as the clock signalgenerated by PLL clock 920. XPBus controller 965 receives the PCK signalafter it has been buffered and operates at the clock speed of PCK. Thebuffered version of the clock signal PCK is used to generate the clocksignal PCKR, the clock signal form the XPBus controller 965 to XPBuscontroller 915. Accordingly, PCKR also has the same frequency as thatgenerated by the PLL clock 920. The synchronous operation of PCK andPCKR provides for improved reliability in the system. In anotherembodiment, PCKR may be generated independently of PCK and may have afrequency different from that of PCK. It is to be noted that even whenPCKR is generated from PCK, the slew between PCK and PCKR cannot beguaranteed because of the unknown cable length used for the XPBus. For acable that is several feet long, the cable propagation delay alone canbe several nano seconds.

As indicated in FIG. 9, PLL clock 970 is asynchronous with the XPBuscontroller 965. Instead, PLL clock 970 independently generates a clocksignal that is used as a PCI clock signal on the secondary PCI bus 980.The secondary PCI bus 980 operates at the same clock speed as theprimary PCI bus 930, namely at a frequency of 33 MHz.

FIG. 10 is a detailed block diagram of one embodiment of the HIC of thepresent invention. As shown in FIG. 10, HIC 1000 comprises buscontroller 1010, translator 1020, transmitter 1030, receiver 1040, a PLL1050, an address/data multiplexer (A/D MUX) 1060, a read/writecontroller (RD/WR Cntl) 1070, a video serial to parallel converter 1080and a CPU control & general purpose input/output latch/driver (CPU CNTL& GPIO latch/driver) 1090.

HIC 1000 is coupled to an optional flash memory BIOS configuration unit1001. Flash memory unit 1001 stores basic input output system (BIOS) andPCI configuration information and supplies the BIOS and PCIconfiguration information to A/D MUX 1060 and RD/WR Control 1070, whichcontrol the programming, read, and write of flash memory unit 1001.

Bus controller 1010 is coupled to the host PCI bus, which is alsoreferred to herein as the primary PCI bus, and manages PCI bustransactions on the host PCI bus. Bus controller 1010 includes a slave(target) unit 1011 and a master unit 1016. Both slave unit 1011 andmaster unit 1016 each include two first in first out (FIFO) buffers,which are preferably asynchronous with respect to each other since theinput and output of the two FIFOs in the master unit 1016 as well as thetwo FIFOs in the slave unit 1011 are clocked by different clocks, namelythe PCI clock and the PCK. Additionally, slave unit 1011 includesencoder 1022 and decoder 1023, while master unit 1016 includes encoder1027 and decoder 1028. The FIFOs 1012, 1013, 1017 and 1018 manage datatransfers between the host PCI bus and the XPBus, which in theembodiment shown in FIG. 10 operate at 33 MHz and 106 MHz, respectively.PCI address/data (AD) from the host PCI bus is entered into FIFOs 1012and 1017 before they are encoded by encoders 1022 and 1023. Encoders1022 and 1023 format the PCI address/data bits to a form more suitablefor parallel to serial conversion prior to transmittal on the XPBus.Similarly, address and data information from the receivers is decoded bydecoders 1023 and 1028 to a form more suitable for transmission on thehost PCI bus. Thereafter the decoded data and address information ispassed through FIFOs 1013 and 1018 prior to being transferred to thehost PCI bus. FIFOs 1012, 1013, 1017 and 1018, allow bus controller 1010to handle posted and delayed PCI transactions and to provide deepbuffering to store PCI transactions.

Bus controller 1010 also comprises slave read/write control (RD/WR Cntl)1014 and master read/write control (RD/WR Cntl) 1015. RD/WR controls1014 and 1015 are involved in the transfer of PCI control signalsbetween bus controller 1010 and the host PCI bus.

Bus controller 1010 is coupled to translator 1020. Translator 1020comprises encoders 1022 and 1027, decoders 1023 and 1028, controldecoder & separate data path unit 1024 and control encoder & merge datapath unit 1025. As discussed above encoders 1022 and 1027 are part ofslave data unit 1011 and master data unit 1016, respectively, receivePCI address and data information from FIFOs 1012 and 1017, respectively,and encode the PCI address and data information into a form moresuitable for parallel to serial conversion prior to transmittal on theXPBus. Similarly, decoders 1023 and 1028 are part of slave data unit1011 and master data unit 1016, respectively, and format address anddata information from receiver 1040 into a form more suitable fortransmission on the host PCI bus. Control encoder & merge data path unit1025 receives PCI control signals from the slave RD/WR control 1014 andmaster RD/WR control 1015. Additionally, control encoder & merge datapath unit 1025 receives control signals from CPU CNTL & GPIOlatch/driver 1090, which is coupled to the CPU and north bridge (notshown in FIG. 10). Control encoder & merge data path unit 1025 encodesPCI control signals as well as CPU control signals and north bridgesignals into control bits, merges these encoded control bits andtransmits the merged control bits to transmitter 1030, which thentransmits the control bits on the data lines PD0 to PD3 and control linePCN of the XPBus. Examples of control signals include PCI controlsignals and CPU control signals. A specific example of a control signalis FRAME# used in PCI buses. A control bit, on the other hand is a databit that represents a control signal. Control decoder & separate datapath unit 1024 receives control bits from receiver 1040 which receivescontrol bits on data lines PDR0 to PDR3 and control line PCNR of theXPBus. Control decoder & separate data path unit 1024 separates thecontrol bits it receives from receiver 1040 into PCI control signals,CPU control signals and north bridge signals, and decodes the controlbits into PCI control signals, CPU control signals, and north bridgesignals all of which meet the relevant timing constraints.

Transmitter 1030 receives multiplexed parallel address/data (A/D) bitsand control bits from translator 1020 on the AD[31::0] out and the CNTLout lines, respectively. Transmitter 1030 also receives a clock signalfrom PLL 1050. PLL 1050 takes a reference input clock and generates PCKthat drives the XPBus. PCK is asynchronous with the PCI clock signal andoperates at 106 MHz, twice the speed of the PCI clock of 33 MHz. Thehigher speed is intended to accommodate at least some possible increasesin the operating speed of future PCI buses. As a result of the higherspeed, the XPBus may be used to interface two PCI or PCI-like busesoperating at 106 MHz rather than 33 MHz or having 104 rather than 32multiplexed address/data lines.

The multiplexed parallel A/D bits and some control bits input totransmitter 1030 are serialized by parallel to serial converters 1032 oftransmitter 1030 into 10 bit packets. These bit packets are then outputon data lines PD0 to PD3 of the XPBus. Other control bits are serializedby parallel to serial converter 1033 into 10 bit packets and send out oncontrol line PCN of the XPBus.

A 10× multiplier 1031 receives PCK, multiplies it by a factor of 10 andfeeds a clock signal 10 times greater than PCK into the parallel toserial converters 1032 and 1033. The parallel to serial converters 1032and 1033 perform bit shifting at 10 times the PCK rate to serialize theparallel bits into 10 bit packets. As the parallel to serial converters1032 and 1033 shift bits at 10 times the PCK rate, the bit rate for theserial bits output by the parallel to serial converters is 10 timeshigher than PCK rate, i.e., 1060 MHz. However, the rate at which datapackets are transmitted on the XPBus is the same as the PCK rate, i.e.,106 MHz. As the PCI buses operate at a clock and bit rate of 33 MHz, theXPBus has a clock rate that is twice as large and a bit rate per bitline (channel) that is 100 times as large as that of the PCI buses whichit interfaces.

Receiver 1040 receives serial bit packets on data lines PDR0 to PDR3 andcontrol line PCNR. Receiver 1040 also receives PCKR on the XPBus as wellas the clock signal PCK from PLL 1050. The synchronizer (SYNC) 1044 ofreceiver 1040 synchronizes the clock signal PCKR to the locallygenerated clock signal, PCK, in order to capture the bits received fromthe XPBus into PCK clock timing.

Serial to parallel converters 1042 convert the serial bit packetsreceived on lines PDR0 to PDR3 into parallel address/data and controlbits that are sent to decoders 1023 and 1028 and control decoder andseparate data path unit 1024, respectively. Serial to parallel converter1043 receives control bit packets from control line PCNR, converts themto parallel control bits and sends the parallel control bits to controldecoder & separate data path 1024.

A 10× multiplier 1041 receives PCKR, multiplies it by a factor of 10 andfeeds a clock signal 10 times greater than PCKR into the serial toparallel converters 1042 and 1043. Because the bits on PDR0 to PDR3 andPCNR are transmitted at a bit rate of 10 times the PCKR rate, the serialto parallel converters 1042 and 1043 perform bit shifting at 10 timesthe PCKR rate to convert the 10 bit packets into parallel bits. It is tobe noted that the rate at which bit packets are transmitted on the XPBusis the same as the PCKR rate, i.e., 106 MHz. The parallel data andcontrol bits are thereafter sent to decoders 1023 and 1028 by way of theAD[3::0] in line and to control decoder & separate data path unit 1024by way of CNTL in lines, respectively.

Reset control unit 1045 of HIC 1000 receives the signal RESET#, which isan independent system reset signal, on the reset line RESET#. Resetcontrol unit 1045 then transmits the reset signal to the CPU CNTL & GPIOlatch/driver unit 1090.

As may be noted from the above, the 32 line host and secondary PCI busesare interfaced by 10 XPBus lines (PD0, PD1, PD2, PD3, PCN, PDR0, PDR1,PDR2, PDR3, PCNR). Therefore, the interface channel, XPBus, of thepresent invention uses fewer lines than are contained in either of thebuses which it interfaces, namely the PCI buses. XPBus is able tointerface such PCI buses without backup delays because the XPBusoperates at a clock rate and a per line (channel) bit rate that arehigher than those of the PCI buses.

In addition to receiving a reset signal, the CPU CNTL & GPIOlatch/driver 1090 is responsible for latching input signals from the CPUand north bridge and sending the signals to the translator. It alsotakes decoded signals from the control decoder & separate data path unit1024 and drives the appropriate signals for the CPU and north bridge.

In the embodiment shown in FIG. 10, video serial to parallel converter1080 is included in HIC 1000. In another embodiment, video serial toparallel converter 1080 may be a separate unit from the HIC 1000. Videoserial to parallel converter 1080 receives serial video data on line VPDand a video clock signal VPCK from line VPCK of video bus 1081. It thenconverts the serial video data into 16 bit parallel video port data andthe appropriate video port control signals, which it transmits to thegraphics controller (not shown in FIG. 10) on the video port data[0::15] and video port control lines, respectively.

HIC 1000 handles the PCI bus control signals and control bits from theXPBus representing PCI control signals in the following ways:

-   -   1. HIC 1000 buffers clocked control signals from the host PCI        bus, encodes them into control bits and sends the encoded        control bits to the XPBus;    -   2. HIC 1000 manages the signal locally; and    -   3. HIC 1000 receives control bits from XPBus, translates the        control bits into PCI control signals and sends the PCI control        signals to the host PCI bus.

FIG. 11 is a detailed block diagram of one embodiment of the PIC of thepresent invention. PIC 1100 is nearly identical to HIC 1000 in itsfunction, except that HIC 1000 interfaces the host PCI bus to the XPBuswhile PIC 1100 interfaces the secondary PCI bus to the XPBus. Similarly,the components in PIC 1100 serve the same function as theircorresponding components in HIC 1000. Reference numbers for componentsin PIC 1100 have been selected such that a component in PIC 1100 and itscorresponding component in HIC 1000 have reference numbers that differby 500 and have the same two least significant digits. Thus for example,the bus controller in PIC 1100 is referenced as bus controller 1110while the bus controller in HIC 1000 is referenced as bus controller1010. As many of the elements in PIC 1100 serve the same functions asthose served by their corresponding elements in HIC 1000 and as thefunctions of the corresponding elements in HIC 1000 have been describedin detail above, the function of elements of PIC 1100 havingcorresponding elements in HIC 1000 will not be further described herein.Reference may be made to the above description of FIG. 10 for anunderstanding of the functions of the elements of PIC 1100 havingcorresponding elements in HIC 1000.

As suggested above, there are also differences between HIC 1000 and PIC1100. Some of the differences between HIC 1000 and PIC 1100 include thefollowing. First, receiver 1140 in PIC 1100, unlike receiver 1040 in HIC1000, does not contain a synchronization unit. As mentioned above, thesynchronization unit in HIC 1000 synchronizes the PCKR clock to the PCKclock locally generated by PLL 1050. PIC 1100 does not locally generatea PCK clock and therefore, it does not have a locally generated PCKclock with which to synchronize the PCK clock signal that it receivesfrom HIC 1000. Another difference between PIC 1100 and HIC 1000 is thefact that PIC 1100 contains a video parallel to serial converter 1189whereas HIC 1000 contains a video serial to parallel converter 1080.Video parallel to serial converter 1189 receives 16 bit parallel videocapture data and video control signals on the Video Port Data [0::15]and Video Port Control lines, respectively, from the video capturecircuit (not shown in FIG. 11) and converts them to a serial video datastream that is transmitted on the VPD line to the HIC. The video capturecircuit may be any type of video capture circuit that outputs a 16 bitparallel video capture data and video control signals. Anotherdifference lies in the fact that PIC 1100, unlike HIC 1000, contains aclock doubler 1182 to double the video clock rate of the video clocksignal that it receives. The doubled video clock rate is fed into videoparallel to serial converter 1182 through buffer 1183 and is sent toserial to parallel converter 1080 through buffer 1184. Additionally,reset control unit 1135 in PIC 1100 receives a reset signal from the CPUCNTL & GPIO latch/driver unit 1190 and transmits the reset signal on theRESET# line to the HIC 1000 whereas reset control unit 1045 of HIC 1000receives the reset signal and forwards it to its CPU CNTL & GPIOlatch/driver unit 1090 because, in the above embodiment, the resetsignal RESET# is unidirectionally sent from the PIC 1100 to the HIC1000.

Like HIC 1000, PIC 1100 handles the PCI bus control signals and controlbits from the XPBus representing PCI control signals in the followingways:

-   -   1. PIC 1100 buffers clocked control signals from the secondary        PCI bus, encodes them and sends the encoded control bits to the        XPBus;    -   2. PIC 1100 manages the signal locally; and    -   3. PIC 1100 receives control bits from XPBus, translates them        into PCI control signals and sends the PCI control signals to        the secondary PCI bus.

PIC 1100 also supports a reference arbiter on the secondary PCI Bus tomanage the PCI signals REQ# and GNT#.

FIG. 12 is a table showing the symbols, signals, data rate anddescription of signals on the XPBus, where RTN indicates a ground (GND)reference. In the above tables, P&D stands for plug and display and is atrademark of the Video Electronics Standards Association (VESA) for thePlug and Display standard, DDC2:SCL and DDC2:SDA stand for the VESAdisplay data channel (DDC) standard 2 clock and data signals,respectively, SV stands for super video, V33 is 3.3 volts, and V5 is 5.0volts. TMDS stands for Transition Minimized Differential Signaling andis a trademark of Silicon Images and refers to their Panel Linktechnology, which is in turn a trademark for their LVDS technology. TMDSis used herein to refer to the Panel Link technology or technologiescompatible therewith.

FIG. 13 is a table showing the information transmitted on the XPBusduring two clock cycles of the XPBus in one embodiment of the presentinvention where 10 data bits are transmitted in each clock cycle of theXPBus. In FIG. 13, A00 to A31 represent 32 bits of PCI address A[31::0],D00 to D31 represent 32 bits of PCI data D[31::0], BS0 to BS3 represent4 bits of bus status data indicating the status of the XPBus, CM0# toCM3# represent 4 bits of PCI command information, BE0# to BE3# represent4 bits of PCI byte enable information, and CN0 to CN9 represent 10 bitsof control information sent in each clock cycle. As shown in FIG. 13,for each of lines PD0 to PD3, the 10 bit data packets contain one BSbit, one CM/BE bit, and eight A/D bits. For the PCN line, the 10 bitdata packet contains 10 CN bits. The first clock cycle shown in FIG. 13comprises an address cycle in which 4 BS bits, 4 CM bits, 32 A bits and10 CN bits are sent. The second clock cycle comprises a data cycle inwhich 4 BS bits, 4 BE bits, 32 D bits and 10 CN bits are sent. The bitstransmitted on lines PD0 to PD3 represent 32 PCI AD[31::0] signals, 4PCI C/BE# [3::0] signals, and part of the function of PCI controlsignals, such as FRAME#, IRDY#, and TRDY#.

In the embodiment shown in FIG. 13, BS0 to BS3 are sent at the beginningof each clock cycle. The bus status bits indicate the following buscycle transactions: idle, address transfer, write data transfer, readdata transfer, switch XPBus direction, last data transfer, wait, andother cycles.

Bits representing signals transmitted between the CPU and South Bridgemay also be sent on the lines interconnecting the HIC and PIC, such aslines PCN and PCNR. For example, CPU interface signals such as CPUinterrupt (INTR), Address 20 Mask (A20M#), Non-Maskable Interrupt (NMI),System Management Interrupt (SMI#), and Stop Clock (STPCLK#), may betranslated into bit information and transmitted on the XPBus between theHIC and the PIC.

FIG. 14 is a table showing the information transmitted on the XPBusduring four clock cycles of the XPBus in another embodiment of thepresent invention where 10 data bits are transmitted in each clock cycleof the XPBus. In this embodiment, the XPBus clock rate is twice as largeas the PCI clock rate. This allows sending data and address bits everyother XPBus cycle. As can be seen in FIG. 14, there are no address ordata bits transmitted during the second or fourth XPBus clock cycle. Thefact that the XPBus clock rate is higher than the PCI clock rate allowsfor compatibility of the XPBus with possible future expansions in theperformance of PCI bus to higher data transfer and clock rates.

In the embodiment shown in FIG. 14, there are 18 control bits, CN0 toCN17, transmitted in every two XPBus clock cycles. The first bittransmitted on the control line in each XPBus clock cycle indicateswhether control bits CN0 to CN8 or control bits CN9 to CN17 will betransmitted in that cycle. A zero sent at the beginning of a cycle onthe control line indicates that CN0 to CN8 will be transmitted duringthat cycle, whereas a one sent at the beginning of a cycle on thecontrol line indicates that CN9 to CN17 will be transmitted during thatcycle. These bits also indicate the presence or absence of data andaddress bits during that cycle. A zero indicates that address or databits will be transmitted during that cycle whereas a one indicates thatno address or data bits will be transmitted during that cycle.

In one embodiment, BS0 and BS1 are used to encode the PCI signals FRAME#and IRDY#, respectively. Additionally, in one embodiment, BS2 and BS3are used to indicate the clock speed of the computer bus interface andthe type of computer bus interface, respectively. For example, BS2 valueof zero may indicate that a 33 MHz PCI bus of 32 bits is used whereas aBS2 value of one may indicate that a 66 MHz PCI bus of 32 bits is used.Similarly, a BS3 value of zero may indicated that a PCI bus is usedwhereas a BS3 value of one may indicated that another computer interfacebus, such as an Institute of Electronics & Electrical Engineers (IEEE)1394 bus, is used.

FIG. 15 is a schematic diagram of lines PCK, PD0 to PD3, and PCN. Theselines are unidirectional LVDS lines for transmitting clock signals andbits such as those shown in FIGS. 13 and 14 from the HIC to the PIC. Thebits on the PD0 to PD3 and the PCN lines are sent synchronously withinevery clock cycle of the PCK. Another set of lines, namely PCKR, PDR0 toPDR3, and PCNR, are used to transmit clock signals and bits from the PICto HIC. The lines used for transmitting information from the PIC to theHIC have the same structure as those shown in FIG. 15, except that theytransmit data in a direction opposite to that in which the lines shownin FIG. 15 transmit data. In other words they transmit information fromthe PIC to the HIC. The bits on the PDR0 to PDR3 and the PCNR lines aresent synchronously within every clock cycle of the PCKR. Some of theexamples of control information that may be sent in the reversedirection, i.e., on PCNR line, include a request to switch data busdirection because of a pending operation (such as read data available),a control signal change in the target requiring communication in thereverse direction, target busy, and transmission error detected.

The XPBus which includes lines PCK, PD0 to PD3, PCN, PCKR, PDR0 to PDR3,and PCNR, has two sets of unidirectional lines transmitting clocksignals and bits in opposite directions. The first set of unidirectionallines includes PCK, PD0 to PD3, and PCN. The second set ofunidirectional lines includes PCKR, PDR0 to PDR3, and PCNR. Each ofthese unidirectional set of lines is a point-to-point bus with a fixedtransmitter and receiver, or in other words a fixed master and slavebus. For the first set of unidirectional lines, the HIC is a fixedtransmitter/master whereas the PIC is a fixed receiver/slave. For thesecond set of unidirectional lines, the PIC is a fixedtransmitter/master whereas the HIC is a fixed receiver/slave. The LVDSlines of XPBus, a cable friendly and remote system I/O bus, transmitfixed length data packets within a clock cycle.

The XPBus lines, PD0 to PD3, PCN, PDR0 to PDR3 and PCNR, and the videodata and clock lines, VPD and VPCK, are not limited to being LVDS lines,as they may be other forms of bit based lines. For example, in anotherembodiment, the XPBus lines may be IEEE 1394 lines.

It is to be noted that although each of the lines PCK, PD0 to PD3, PCN,PCKR, PDR0 to PDR3, PCNR, VPCK, and VPD is referred to as a line, in thesingular rather than plural, each such line may contain more than onephysical line. For example, in the embodiment shown in FIG. 23, each oflines PCK, PD0 to PD3 and PCN includes two physical lines between eachdriver and its corresponding receiver. The term line, when not directlypreceded by the terms physical or conductive, is herein usedinterchangeably with a signal or bit channel which may consist of one ormore physical lines for transmitting a signal. In the case ofnon-differential signal lines, generally only one physical line is usedto transmit one signal. However, in the case of differential signallines, a pair of physical lines is used to transmit one signal. Forexample, a bit line or bit channel in an LVDS or IEEE 1394 interfaceconsists of a pair of physical lines which together transmit a signal.

A bit based line (i.e., a bit line) is a line for transmitting serialbits. Bit based lines typically transmit bit packets and use a serialdata packet protocol. Examples of bit lines include an LVDS line, anIEEE 1394 line, and a Universal Serial Bus (USB) line.

FIG. 16 is a table showing the names, types, number of pins dedicatedto, and the description of the primary bus PCI signals. The pinsrepresent those between the host PCI bus and the HIC.

In most embodiments, the ACM includes an enclosure such as the onedescribed with the following components, which should not be limiting:

-   -   1) A CPU with cache memory;    -   2) Core logic device or means;    -   3) Main memory;    -   4) A single primary Hard Disk Drive “HDD”) that has a security        program;    -   5) Flash memory with system BIOS and programmable user password;    -   6) Operating System, application software, data files on primary        HDD;    -   7) An interface device and connectors to peripheral console;    -   8) A software controllable mechanical lock, lock control means,        and other accessories.

The ACM connects to a peripheral console with power supply, a displaydevice, an input device, and other elements. Some details of theseelements with the present security system are described in more detailbelow.

FIG. 17 is a simplified layout diagram of a security system for acomputer system according to an embodiment of the present invention.This diagram is merely an illustration and should not limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, modifications, and alternatives. The layout diagramillustrates the top-view of the module 1710, where the backsidecomponents (e.g., Host Interface Controller) are depicted in dashedlines. The layout diagram has a first portion, which includes a centralprocessing unit “CPU”) module 1700, and a second portion, which includesa hard drive module 1720. A common printed circuit board 1737 housesthese modules and the like. Among other features, the ACM includes thecentral processing unit module 1700 with a cache memory 1705, which iscoupled to a north bridge unit 1721, and a host interface controller1701. The host interface controller includes a lock control 1703. Asshown, the CPU module is disposed on a first portion of the attachedcomputer module, and couples to connectors 1717. Here, the CPU module isspatially located near connector 1717.

The CPU module can use a suitable microprocessing unit, microcontroller,digital signal processor, and the like. In a specific embodiment, theCPU module uses, for example, a 400 MHz Pentium II microprocessor modulefrom Intel Corporation and like microprocessors from AMD Corporation,Cyrix Corporation (now National Semiconductor Corporation), and others.In other aspects, the microprocessor can be one such as the CompaqComputer Corporation Alpha Chip, Apple Computer Corporation PowerPC G3processor, and the like. Further, higher speed processors arecontemplated in other embodiments as technology increases in the future.

In the CPU module, host interface controller 1701 is coupled toBIOS/flash memory 1705. Additionally, the host interface controller iscoupled to a clock control logic, a configuration signal, and aperipheral bus. The present invention has a host interface controllerthat has lock control 1703 to provide security features to the presentACM. Furthermore, the present invention uses a flash memory thatincludes codes to provide password protection or other electronicsecurity methods.

The second portion of the attached computer module has the hard drivemodule 1720. Among other elements, the hard drive module includes northbridge 1721, graphics accelerator 1723, graphics memory 1725, a powercontroller 1727, an IDE controller 1729, and other components. Adjacentto and in parallel alignment with the hard drive module is a personalcomputer interface “PCI”) bus 1731, 1732. A power regulator 1735 isdisposed near the PCI bus.

In a specific embodiment, north bridge unit 1721 often couples to acomputer memory, to the graphics accelerator 1723, to the IDEcontroller, and to the host interface controller via the PCI bus.Graphics accelerator 1723 typically couples to a graphics memory 1723,and other elements. IDE controller 1729 generally supports and providestiming signals necessary for the WDE bus. In the present embodiment, theIDE controller is embodied as a 643U2 PCI-to IDE chip from CMDTechnology, for example. Other types of buses than IDE are contemplated,for example EIDE, SCSI, 1394, and the like in alternative embodiments ofthe present invention.

The hard drive module or mass storage unit 1720 typically includes acomputer operating system, application software program files, datafiles, and the like. In a specific embodiment, the computer operatingsystem may be the Windows98 operating system from Microsoft Corporationof Redmond Wash. Other operating systems, such as WindowsNT, MacOS8,Unix, and the like are also contemplated in alternative embodiments ofthe present invention. Further, some typical application softwareprograms can include Office98 by Microsoft Corporation, Corel PerfectSuite by Corel, and others. Hard disk module 1720 includes a hard diskdrive. The hard disk drive, however, can also be replaced by removablehard disk drives, read/write CD ROMs, flash memory, floppy disk drives,and the like. A small form factor, for example 2.5″, is currentlycontemplated, however, other form factors, such as PC card, and the likeare also contemplated. Mass storage unit 1720 may also support otherinterfaces than IDE. Among other features, the computer system includesan ACM with security protection. The ACM connects to the console, whichhas at least the following elements, which should not be limiting.

-   -   1) Connection to input devices, e.g. keyboard or mouse;    -   2) Connection to display devices, e.g. Monitor;    -   3) Add-on means, e.g. PCI add-on slots;    -   4) Removable storage media subsystem, e.g. Floppy drive, CDROM        drive;    -   5) Communication device, e.g. LAN or modem;    -   6) An interface device and connectors to ACM;    -   7) A computer module bay with a notch in the frame for ACM's        lock; and    -   8) Power supply and other accessories.

As noted, the computer module bay is an opening in a peripheral consolethat receives the ACM. The computer module bay provides mechanicalsupport and protection to ACM. The module bay also includes, among otherelements, a variety of thermal components for heat dissipation, a framethat provides connector alignment, and a lock engagement, which securesthe ACM to the console. The bay also has a printed circuit board tomount and mate the connector from the ACM to the console. The connectorprovides an interface between the ACM and other accessories.

FIG. 18 is a simplified block diagram 1800 of a security system for acomputer module according to an embodiment of the present invention.This diagram is merely an illustration and should not limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, modifications, and alternatives. The block diagram1800 has a variety of features such as those noted above, as well asothers. In the present diagram, different reference numerals are used toshow the operation of the present system.

The block diagram is an attached computer module 1800. The module 1800has a central processing unit, which communicates to a north bridge1841, by way of a CPU bus 1827. The north bridge couples to main memory1823 via memory bus 1829. The main memory can be any suitable high speedmemory device or devices such as dynamic random access memory “DRAM”)integrated circuits and others. The DRAM includes at least 32 Meg. or617 Meg. and greater of memory, but can also be less depending upon theapplication. Alternatively, the main memory can be coupled directly withthe CPU in some embodiments. The north bridge also couples to a graphicssubsystem 1815 via bus 1842. The graphics subsystem can include agraphics accelerator, graphics memory, and other devices. Graphicssubsystem transmits a video signal to an interface connector, whichcouples to a display, for example.

The attached computer module also includes a primary hard disk drivethat serves as a main memory unit for programs and the like. The harddisk can be any suitable drive that has at least 2 GB and greater. Asmerely an example, the hard disk is a Marathon 2250 (2.25 GB, 2½ inchdrive) product made by Seagate Corporation of Scotts Valley, but can beothers. The hard disk communicates to the north bridge by way of a harddisk drive controller and bus lines 1802 and 1831. The hard disk drivecontroller couples to the north bridge by way of the host PCI bus, whichconnects bus 1837 to the north bridge. The hard disk includes computercodes that implement a security program according to the presentinvention. Details of the security program are provided below.

The attached computer module also has a flash memory device 1805 with aBIOS. The flash memory device 1805 also has codes for a user passwordthat can be stored in the device. The flash memory device generallypermits the storage of such password without a substantial use of power,even when disconnected. As merely an example, the flash memory devicehas at least 4 Meg. or greater of memory, or 16 Meg. or greater ofmemory. A host interface controller 1807 communications to the northbridge via bus 1835 and host PCI bus. The host interface controller alsohas a lock control 1809, which couples to a lock. The lock is attachedto the module and has a manual override to the lock on the hostinterface controller in some embodiments. Host interface controller 1807communicates to the console using bus 1811, which couples to connection1813.

In a preferred embodiment, the present invention uses a passwordprotection scheme to electronically prevent unauthorized access to thecomputer module. The present password protection scheme uses acombination of software, which is a portion of the security program, anda user password, which can be stored in the flash memory device 1805. Byway of the flash memory device, the password does not become erased byway of power failure or the lock. The password is substantially fixed incode, which cannot be easily erased. Should the user desire to changethe password, it can readily be changed by erasing the code, which isstored in flash memory and a new code (i.e., password) is written intothe flash memory. An example of a flash memory device can include aIntel Flash 28F800F3 series flash, which is available in 8 Mbit and 16Mbit designs. Other types of flash devices can also be used, however.Details of a password protection method are further explained below byway of the FIGS.

In a specific embodiment, the present invention also includes areal-time clock 1810 in the ACM, but is not limited. The real-time clockcan be implemented using a reference oscillator 14.31818 MHz 1808 thatcouples to a real-time clock circuit. The real-time clock circuit can bein the host interface controller. An energy source 1806 such as abattery can be used to keep the real-time clock circuit running evenwhen the ACM has been removed from the console. The real-time clock canbe used by a security program to perform a variety of functions. Asmerely an example, these functions include: (1) fixed time period inwhich the ACM can be used, e.g., ACM cannot be used at night; (2)programmed ACM to be used after certain date, e.g., high securityprocedure during owner's vacation or non use period; (3) other usessimilar to a programmable time lock. Further details of the presentreal-time clock are described in the application listed under Ser. No.09/183,816 noted above.

In still a further embodiment, the present invention also includes apermanent password or user identification code to identify the computermodule. In one embodiment, the permanent password or user code is storedin a flash memory device. Alternatively, the permanent password or usercode is stored in the central processing unit. The password or user codecan be placed in the device upon manufacture of such device.Alternatively, the password or user code can be placed in the device bya one time programming techniques using, for example, fuses or the like.The present password or user code provides a permanent “finger print” onthe device, which is generally hardware. The permanent finger print canbe used for identification purposes for allowing the user of thehardware to access the hardware itself, as well as other systems. Theseother systems include local and wide area networks. Alternatively, thesystems can also include one or more servers. The present password anduser identification can be quite important for electronic commerceapplications and the like. In one or more embodiments, the permanentpassword or user code can be combined with the password on flash memoryfor the security program, which is described below in more detail.

In one aspect of the invention, the user password is programmable. Thepassword can be programmable by way of the security program. Thepassword can be stored in a flash memory device within the ACM.Accordingly, the user of the ACM and the console would need to have theuser password in order to access the ACM. In the present aspect, thecombination of a security program and user password can provide the usera wide variety of security functions as follows:

-   -   1) Auto-lock capability when ACM is inserted into CMB;    -   2) Access privilege of program and data;    -   3) Password matching for ACM removal; and    -   4) Automatic HDD lock out if tempering is detected.

In still a further embodiment, the present invention also includes amethod for reading a permanent password or user identification code toidentify the computer module. In one embodiment, the permanent passwordor user code is stored in a flash memory device. Alternatively, thepermanent password or user code is stored in the central processingunit. The password or user code can be placed in the device uponmanufacture of such device. Alternatively, the password or user code canbe placed in the device by a one time programming techniques using, forexample, fuses or the like. The present password or user code provides apermanent “finger print” on the device, which is generally hardware. Thepermanent finger print can be used for identification purposes forallowing the user of the hardware to access the hardware itself, as wellas other systems. These other systems include local and wide areanetworks. Alternatively, the systems can also include one or moreservers. The present method allows a third party confirm the user by wayof the permanent password or user code. The present password and useridentification can be quite important for electronic commerceapplications and the like, which verify the user code or password. Inone or more embodiments, the permanent password or user code can becombined with the password on flash memory for the security program.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

1. A computer system comprising: a console comprising a power supply, afirst coupling site and a second coupling site, each coupling sitecomprising a connector and a slot, the console being an enclosurehousing the coupling sites, a serial communication hub controllerpowered by the power supply, and a plurality of computer modules; eachcomputer module coupled to one of the coupling site through theconnector and the slot, comprising a processing unit, a flash memorydevice configured to store a password for controlling access to thecomputer module, a main memory coupled to the processing unit, andwherein each of the computer modules is substantially similar in designto each other and operates fully independent of each other; and whereineach computer module communicates with the console through two sets ofunidirectional serial, differential signal channels which transmit datain opposite directions.
 2. The computer system of claim 1 wherein eachcomputer module further comprises a communication controller coupled tothe serial communication controller in the console adapted to transferdata between any two of the computer modules and to an external network.3. The computer system of claim 1 further comprises a hard disk drivecoupled to the computer module.
 4. The computer system of claim 1wherein the computer module further comprises an interface controllercoupled to a differential signal channel for communicating an encodedserial bit stream of Peripheral Component Interconnect (PCI) bustransaction.
 5. The computer system of claim 4 wherein the serial bitstream of PCI bus transaction comprises encoded PCI address and databits.
 6. A computer system comprising: a console comprising a powersupply, a first coupling site and a second coupling site, each couplingsite comprising a connector and a slot, the console being an enclosurehousing the coupling sites, an Ethernet hub controller coupled to anexternal network and powered by the power supply, and a plurality ofcomputer modules; each computer module coupled to one of the couplingsite through the connector and the slot, comprising a processing unit, aflash memory device configured to store a password for controllingaccess to the computer module, a main memory coupled to the processingunit, an interface controller coupled to a differential signal channelfor communicating an encoded serial data stream of Peripheral ComponentInterconnect (PCI) bus transaction, and a network controller coupled tothe Ethernet hub controller through the connector of the coupling site,wherein each of the computer modules is substantially similar in designto each other.
 7. The computer system of claim 6 wherein thedifferential signal channel comprises two sets of unidirectional serialbit channels which transmit data in opposite directions.
 8. The computersystem of claim 6 wherein the encoded serial bit stream comprises 10 bitpackets.
 9. The computer system of claim 6 wherein the serial bit streamof PCI bus transaction comprises encoded PCI address and data bits. 10.The computer system of claim 6 wherein the Ethernet hub controlleradapted to transfer data between any two of the computer modules and tothe external network.
 11. A computer system comprising: a consolecomprising a power supply, a first coupling site and a second couplingsite, each coupling site comprising a connector and a slot, the consolebeing a first enclosure housing an Ethernet hub controller powered bythe power supply, each coupling site, and a plurality of computermodules, each coupled to one of the coupling sites through the connectorand the slot; each computer module comprising a processing unit, a mainmemory coupled to the processing unit, a mass storage device storing asecurity program that provides password protection for the computermodule, an interface controller coupled to a differential signal channelfor communicating an encoded serial data stream of Peripheral ComponentInterconnect (PCI) bus transaction, and an Ethernet controller coupledto the Ethernet hub controller through the connector of the couplingsite; and wherein each of the computer modules operates fullyindependent of each other.
 12. The computer system of claim 11 whereinthe differential signal channel comprises two sets of unidirectionalserial channels which transmit data in opposite directions.
 13. Thecomputer system of claim 11 wherein the Ethernet controllers of thecomputer modules are used for sharing peripheral devices residing in theconsole.
 14. The computer system of claim 12 wherein each of theunidirectional serial channels comprises one or more pairs ofdifferential signal lines.
 15. The computer system of claim 11 whereinthe serial bit stream of PCI bus transaction comprises encoded PCIaddress and data bits.
 16. A computer system comprising: a consolecomprising a power supply, a first coupling site and a second couplingsite, each coupling site comprising a connector and a slot, the consolebeing a first enclosure housing the coupling sites, a serialcommunication hub controller powered by the power supply, and aplurality of computer modules; each computer module coupled to one ofthe coupling site through the connector and the slot, comprising aprocessing unit, a main memory coupled to the processing unit, a massstorage device storing a security program that provides passwordprotection for the computer module, a communication controller coupledto the serial communication hub controller through the connector of thecoupling site, and an interface controller coupled to a differentialsignal channel for communicating encoded serial data stream ofPeripheral Component Interconnect (PCI) bus transaction; wherein each ofthe computer modules operates fully independent of each other.
 17. Thecomputer system of claim 16 wherein the encoded serial bit streamcomprises 10 bit packets.
 18. The computer system of claim 16 whereinthe interface controller couples to a flash memory with PCIconfiguration information.
 19. The computer system of claim 16 whereinthe computer module further comprises a second enclosure and a hard diskdrive wherein the second enclosure houses the hard disk drive.
 20. Thecomputer system of claim 16 wherein the serial bit stream of PCI bustransaction comprises encoded PCI address and data bits.
 21. A computersystem comprising: a console comprising a video switch, a first couplingsite and a second coupling site, each coupling site comprising aconnector and a slot; the console being an enclosure housing the videoswitch, an Ethernet hub controller coupled to an external network, and aplurality of computer modules; each computer module coupled to one ofthe coupling sites through the connector and the slot, and comprising aprocessing unit, a main memory coupled to the processing unit, a massstorage device storing a security program that provides passwordprotection for the computer module, a graphics controller coupled to thevideo switch, and an interface controller coupled to a differentialsignal channel of two unidirectional serial bit streams which transmitdata in opposite directions for communicating encoded serializedPeripheral Component Interconnect (PCI) bus transaction data; whereineach of the computer modules operates fully independent of each other.22. The computer system of claim 21 wherein the interface controllercouples to a flash memory with PCI configuration information.
 23. Thecomputer system of claim 21 wherein the serial bit stream comprises oneor more pairs of differential signal lines.
 24. The computer system ofclaim 21 wherein the serial bit stream comprises 10 bit packets.
 25. Thecomputer system of claim 21 wherein the serial bit stream comprises PCIbus transaction with encoded PCI address and data bits.
 26. A computersystem comprising: a console comprising an Ethernet hub controller, afirst coupling site and a second coupling site, each coupling sitecomprising a connector and a slot, the console being an enclosurehousing the Ethernet hub controller, each coupling site, and a pluralityof computer modules, each coupled to one of the coupling sites throughthe connector and the slot; each computer module comprising a processingunit, a main memory coupled to the processing unit, a mass storagedevice storing a security program that provides password protection forthe computer module, an interface controller coupled to a differentialsignal channel for communicating encoded serial bit stream of PeripheralComponent Interconnect (PCI) bus transaction, and an Ethernet controllercoupled to the Ethernet hub controller through the connector of thecoupling site for communication between the computer modules; whereineach of the computer modules operates independent of each other, andwherein one of the computer modules can replace another one of thecomputer modules in operation.
 27. The computer system of claim 26wherein the interface controller couples to a flash memory with PCIconfiguration information.
 28. The computer system of claim 26 whereinthe Ethernet controllers of the computer modules are used for sharingperipheral devices residing in the console.
 29. The computer system ofclaim 26 wherein the differential signal channel comprises two sets ofunidirectional serial bit channels which transmit data in oppositedirections.
 30. The computer system of claim 26 wherein the serial bitstream of PCI bus transaction comprises encoded PCI address and databits.
 31. A computer system comprising: a console comprising a firstcoupling site, and a second coupling site, each coupling site comprisinga connector and a slot; the console being an enclosure housing eachcoupling site, and a plurality of computer modules; each computer modulecoupled to the coupling site through the connector and the slot, andcomprising a processing unit, a main memory coupled to the processingunit, a mass storage device storing a security program that providespassword protection for the computer module, an interface controllercoupled to a differential signal channel for communicating an encodedserial bit stream of Peripheral Component Interconnect (PCI) bustransaction, and a SCSI hard disk drive; wherein each of the computermodules is substantially similar in design to each other, and whereinone of the computer modules can provide protection against failure ofanother one of the computer modules.
 32. The computer system of claim 31wherein the encoded serial bit stream comprises 10 bit packets.
 33. Thecomputer system of claim 31 wherein the SCSI hard disk drive isremovable while the computer module is in operation.
 34. The computersystem of claim 31 wherein the interface controller couples to a flashmemory with PCI configuration information.
 35. The computer system ofclaim 31 wherein the serial bit stream of PCI bus transaction comprisesencoded PCI address and data bits.
 36. A computer system comprising: aconsole comprising an Ethernet controller coupled to an externalnetwork, a keyboard/mouse multi-port switch, a first coupling site and asecond coupling site, each coupling site comprising a connector and aslot, the console being an enclosure housing the Ethernet controller,each coupling site, and a plurality of computer modules, each coupled toone of the coupling sites through the connector and the slot; eachcomputer module comprising a processing unit, a main memory coupled tothe processing unit, an interface controller coupled to a differentialsignal channel for communicating encoded serial bit stream of PeripheralComponent Interconnect (PCI) bus transaction, and a mass storage devicestoring a security program that provides password protection for thecomputer module; wherein each of the computer modules operates fullyindependent of each other; and wherein the keyboard/mouse multi-portswitch switches between keyboard/mouse connection of the computermodules based on a command from a user.
 37. The computer system of claim36 wherein the differential signal channel comprises two sets ofunidirectional serial bit channels which transmit data in oppositedirections.
 38. The computer system of claim 36 wherein the interfacecontroller couples to a flash memory with PCI configuration information.39. The computer system of claim 36 wherein the serial bit stream of PCIbus transaction comprises encoded PCI address and data bits.
 40. Thecomputer system of claim 36 wherein the command from the user is in theform of either a key on the keyboard or an icon on the screen that themouse can click on.
 41. A computer system comprising: a consolecomprising a first coupling site, a second coupling site, each couplingsite comprising a connector, the console being an enclosure that iscapable of housing each coupling site, a serial communication hubcontroller coupled to an external network, and a plurality of computermodules inserted into said console; each computer module coupled to oneof the connectors of the console and comprising, a processing unit, aflash memory device configured to store a password for controllingaccess to the computer module, a communication controller coupled to theserial communication hub controller, a main memory coupled to theprocessing unit, an interface controller coupled to a differentialsignal channel for communicating encoded serial bit stream of PeripheralComponent Interconnect (PCI) bus transaction, and wherein each of thecomputer modules provide independent processing in the computer system;and wherein one of the computer modules is configured to provideprotection against failure of another of the plurality of computermodules.
 42. The computer system of claim 41 wherein the differentialsignal channel comprises two sets of unidirectional serial bit channelswhich transmit data in opposite directions.
 43. The computer system ofclaim 41 wherein the interface controller couples to a flash memory withPCI configuration information.
 44. The computer system of claim 41wherein the serial bit stream of PCI bus transaction comprises encodedPCI address and data bits.
 45. The computer system of claim 41 furthercomprises a hard disk coupled to the computer module.
 46. A computersystem comprising: a console comprising a power supply, a first couplingsite, and a second coupling site, each coupling site comprising aconnector and a slot, the console being an enclosure housing eachcoupling site, a plurality of computer modules, each coupled to one ofthe coupling sites through the connector and the slot; each computermodule comprising a processing unit, a flash memory device configured tostore a password for controlling access to the computer module, a mainmemory coupled to the processing unit, a graphics controller, and aninterface controller coupled to a differential signal channel forcommunicating encoded serialized bit stream of Peripheral ComponentInterconnect (PCI) bus transaction; wherein each of the computer modulesoperates fully independent of each other; and wherein the differentialsignal channel comprises two sets of unidirectional serial channelswhich transmit data in opposite directions, and wherein one of thecomputer modules can replace another one of the computer modules inoperation.
 47. The computer system of claim 46 wherein the encodedserial bit stream comprises 10 bit packets.
 48. The computer system ofclaim 46 wherein each of the unidirectional serial channels comprisesone or more pairs of differential signal lines.
 49. The computer systemof claim 46 wherein the console further houses a power supply thatsupplies DC power to the Ethernet controller and the computer modules.50. The computer system of claim 46 wherein the serial bit stream of PCIbus transaction comprises encoded PCI address and data bits.
 51. Acomputer system comprising: a console comprising an Ethernet hubcontroller, a first coupling site and a second coupling site, eachcoupling site comprising a connector and a slot, the console being anenclosure housing the Ethernet hub controller and the coupling sites;and more than two computer modules, each coupled to one of the couplingsite through the connector and the slot, comprising a processing unit, amain memory coupled to the processing unit, an Ethernet controllercoupled to the Ethernet hub controller through the connector of thecoupling site for communication between the computer modules, and aninterface controller coupled to a differential signal channel forcommunicating encoded serialized Peripheral Component Interconnect (PCI)bus transaction data; wherein each of the computer modules operatesfully independent of each other; and wherein the differential signalchannel comprises two sets of unidirectional serial channels whichtransmit data in opposite directions; and wherein one of the computermodules is configured to provide protection against failure of any oneof the other computer modules.
 52. The computer system of claim 51wherein the Ethernet controllers of the computer modules are used forsharing peripheral devices residing in the console.
 53. The computersystem of claim 51 wherein the encoded serial bit stream comprises 10bit packets.
 54. The computer system of claim 51 wherein each of theunidirectional serial channels comprises one or more pairs ofdifferential signal lines.
 55. The computer system of claim 51 whereinthe serial bit stream of PCI bus transaction comprises encoded PCIaddress and data bits.
 56. A computer system comprising: a consolecomprising an Ethernet hub controller, a first coupling site and asecond coupling site, the console being an enclosure housing theEthernet hub controller, the coupling sites, and a plurality of computermodules, each coupled to one of the coupling sites; each computer modulecomprising a processing unit, a main memory coupled to the processingunit, an interface controller coupled to a differential signal channelof two unidirectional serial bit streams which transmit data in oppositedirections for communicating encoded serialized Peripheral ComponentInterconnect (PCI) bus transaction data to a connector, and an Ethernetcontroller coupled to the Ethernet hub controller for communicationbetween the computer modules; wherein each of the computer modulesoperates fully independent of each other.
 57. The computer system ofclaim 56 wherein the differential signal channel comprises two sets ofunidirectional serial bit channels which transmit data in oppositedirections.
 58. The computer system of claim 11 wherein the Ethernetcontrollers of the computer modules are used for sharing peripheraldevices residing in the console.
 59. The computer system of claim 56wherein the encoded serial bit stream comprises 10 bit packets.
 60. Thecomputer system of claim 56 wherein the serial bit stream of PCI bustransaction comprises encoded PCI address and data bits.
 61. A computersystem comprising: a console comprising an Ethernet controller coupledto an external network, a video switch, a first coupling site and asecond coupling site, the console being an enclosure housing theEthernet controller, the video switch, each coupling site, and aplurality of computer modules, each coupled to one of the couplingsites; each computer module comprising a processing unit, a main memorycoupled to the processing unit, a graphics controller coupled to thevideo switch, and an interface controller coupled to a differentialsignal channel of two unidirectional serial bit streams which transmitdata in opposite directions for communicating encoded serial PeripheralComponent Interconnect (PCI) bus transaction data to a connector;wherein each of the computer modules operates fully independent of eachother.
 62. The computer system of claim 61 wherein the interfacecontroller couples to a flash memory with PCI configuration information.63. The computer system of claim 61 further comprises a hard disk drivecoupled to the computer module.
 64. The computer system of claim 61wherein the console further houses a power supply that supplies DC powerto the Ethernet controller and the computer modules.
 65. The computersystem of claim 61 wherein the serial bit stream of PCI bus transactioncomprises encoded PCI address and data bits.
 66. A computer systemcomprising: a console comprising a first coupling site and a secondcoupling site, the console being an enclosure housing a serialcommunication hub controller, each coupling site, and a plurality ofcomputer modules, each coupled to one of the coupling sites; eachcomputer module comprising a processing unit, a main memory coupled tothe processing unit, a mass storage device storing a security programthat provide password protection for the computer module, an interfacecontroller coupled to a differential signal channel of twounidirectional serial bit streams which transmit data in oppositedirections for communicating encoded serial Peripheral ComponentInterconnect (PCI) bus transaction data to a connector, and acommunication controller coupled to the serial communication hubcontroller through the connector of the coupling site for communicationbetween the computer modules; wherein each of the computer modulesoperates independent of each other.
 67. The computer system of claim 66wherein the interface controller couples to a flash memory with PCIconfiguration information.
 68. The computer system of claim 66 whereinthe hard disk drive is removable while the computer module is inoperation.
 69. The computer system of claim 66 wherein the encodedserial bit stream comprises 10 bit packets.
 70. The computer system ofclaim 66 wherein the serial bit stream of PCI bus transaction comprisesencoded PCI address and data bits.
 71. A computer system comprising: aconsole comprising a first coupling site, and a second coupling site;the console being an enclosure housing each coupling site, a serialcommunication hub controller coupled to an external network, and aplurality of computer modules, each coupled to one of the couplingsites; each computer module comprising a processing unit, a main memorycoupled to the processing unit, a flash memory device configured tostore a password for controlling access to the computer module, acommunication controller coupled to the serial communication controllerto support communication with the external network, and an interfacecontroller coupled to a differential signal channel of twounidirectional serial bit streams which transmit data in oppositedirections for communicating encoded serial Peripheral ComponentInterconnect (PCI) bus transaction data to a connector; wherein each ofthe computer modules operates fully independent of each other; andwherein one of the computer modules can replace another one of thecomputer modules in operation.
 72. The computer system of claim 71wherein the interface controller couples to a flash memory with PCIconfiguration information.
 73. The computer system of claim 71 furthercomprises a hard disk drive coupled to the computer module.
 74. Thecomputer system of claim 71 wherein the serial bit stream comprises 10bit packets.
 75. The computer system of claim 71 wherein the serial bitstream of PCI bus transaction comprises encoded PCI address and databits.
 76. A computer system comprising: a console comprising a firstcoupling site and a second coupling site, each coupling site comprisinga connector and a slot, the console being a first enclosure housing eachcoupling site, and a plurality of computer modules, each coupled to oneof the coupling sites through the connector and the slot; each computermodule comprising a processing unit, a main memory coupled to theprocessing unit, a flash memory device configured to store a passwordfor controlling access to the computer module, an interface controllercoupled to a differential signal channel for communicating an encodedserial bit stream of Peripheral Component Interconnect (PCI) bustransaction, and wherein each of the computer modules operates fullyindependent of each other; and wherein the differential signal channelcomprises two sets of unidirectional serial channels which transmit 10bit packets in opposite directions.
 77. The computer system of claim 76wherein the interface controller couples to a flash memory with PCIconfiguration information.
 78. The computer system of claim 76 whereineach of the unidirectional serial channels comprises one or more pairsof differential signal lines.
 79. The computer system of claim 76wherein the serial bit stream of PCI bus transaction comprises encodedPCI address and data bits.
 80. The computer system of claim 76 whereinthe console further houses a power supply that supplies DC power to theEthernet controller and the computer modules.
 81. A computer systemcomprising: a console comprising an Ethernet controller coupled to anexternal network, a first coupling site and a second coupling site, eachcoupling site comprising a connector and a slot, the console being anenclosure housing the Ethernet controller, each coupling site, and aplurality of computer modules, each coupled to one of the coupling sitesthrough the connector and the slot; each computer module comprising aprocessing unit, a main memory coupled to the processing unit, a flashmemory device configured to store a password for controlling access tothe computer module, a SCSI hard disk drive, and an interface controllercoupled to a differential signal channel for communicating encodedserial bit stream of Peripheral Component Interconnect (PCI) bustransaction; wherein each of the computer modules operates independentof each other; and wherein the differential signal channel couples tothe console through the connector of the coupling site; and wherein theencoded serial bit stream transmits 10 bit packets.
 82. The computersystem of claim 81 wherein the interface controller couples to a flashmemory with PCI configuration information.
 83. The computer system ofclaim 81 wherein the SCSI hard disk drive is removable while thecomputer module is in operation.
 84. The computer system of claim 81wherein the console further houses a power supply that supplies DC powerto the Ethernet controller and the computer modules.
 85. The computersystem of claim 81 wherein the serial bit stream of PCI bus transactioncomprises encoded PCI address and data bits.
 86. A computer systemcomprising: a console comprising a first coupling site and a secondcoupling site, each coupling site comprising a connector and a slot, theconsole being an enclosure housing each coupling site, a serialcommunication controller, and a plurality of computer modules; eachcomputer module coupled to one of the coupling sites through theconnector and the slot; each computer module comprising a processingunit, a main memory coupled to the processing unit, a flash memorydevice configured to store a password for controlling access to thecomputer module, an interface controller coupled to a differentialsignal channel of two unidirectional serial bit streams which transmitdata in opposite directions for communicating encoded serial, 10 bitpacket data stream of Peripheral Component Interconnect (PCI) bustransaction; wherein each of the computer modules operates independentof each other.
 87. The computer system of claim 86 further comprises ahard disk drive coupled to the computer module.
 88. The computer systemof claim 86 wherein the encoded PCI bus transaction comprises encodedPCI address and data bits.
 89. A computer system comprising: a consolecomprising a first coupling site and a second coupling site, eachcoupling site comprising a connector and a slot, the console being anenclosure housing each coupling site, and a plurality of computermodules; each computer module coupled to one of the coupling sitesthrough the connector and the slot; each computer module comprising aprocessing unit, a main memory coupled to the processing unit, a flashmemory device configured to store a password for controlling access tothe computer module, a mass storage device coupled to the processingunit, an interface controller coupled to a differential signal channelof two unidirectional serial bit streams which transmit data in oppositedirections for communicating encoded serial, 10 bit packet data streamof Peripheral Component Interconnect (PCI) bus transaction; and whereineach of the computer modules operates independent of each other; andwherein one of the computer modules can replace another one of thecomputer modules in operation.
 90. The computer system of claim 89wherein the encoded PCI bus transaction comprises encoded PCI addressand data bits.
 91. The computer system of claim 89 wherein each of theunidirectional serial differential signal channels comprises one or morepairs of differential signal lines.
 92. A computer system comprising: aconsole comprising a first coupling site and a second coupling site, theconsole being an enclosure housing each coupling site, and more than twocomputer modules; each computer module coupled to one of the couplingsites; each computer module comprising a processing unit, a main memorycoupled to the processing unit, a flash memory device configured tostore a password for controlling access to the computer module, a massstorage device coupled to the processing unit, an interface controllercoupled to a differential signal channel of two unidirectional serialbit streams which transmit data in opposite directions for communicatingencoded serial bit stream of Peripheral Component Interconnect (PCI) bustransaction to a connector; and wherein each of the computer modulesoperates independent of each other; and wherein one of the computermodules is configured to provide protection against failure of any oneof the other computer modules.
 93. The computer system of claim 92wherein the encoded PCI bus transaction comprises encoded PCI addressand data bits.
 94. The computer system of claim 92 wherein each of theunidirectional serial differential signal channels comprises one or morepairs of differential signal lines.